The richest people on the planet got even richer in 2012, adding US$241 billion to their collective net worth.

According to the Bloomberg Billionaires Index, a daily ranking of the world's 100 wealthiest individuals, the aggregate net worth of the world's top moguls stood at US$1.9 trillion at the market close on December 31.

Retail and telecommunications fortunes surged about 20 per cent on average during the year. Of the 100 people who appeared on the final ranking of 2012, only 16 registered a net loss for the year.

Amancio Ortega, the Spaniard who founded retailer Inditex, was the year's biggest gainer. The 76-year-old tycoon's fortune increased US$22.2 billion to US$57.5 billion, according to the index, as shares of Inditex, operator of the Zara clothing chain, rose 66.7 per cent.

Global stocks soared in 2012. The MSCI World Index gained 13.2 per cent during the year to close at 1338.50 on December 31. The Standard and Poor's 500 Index rose 13.4 per cent to close at 1426.19.

Carlos Slim, the telecommunications magnate who controls Mexico's America Movil, maintained his title as the richest person on earth for the year. The 72-year-old's net worth rose US$13.4 billion - or 21.6 per cent - last year, making him the second-biggest gainer by dollars.

US software mogul Bill Gates, 57, ranks second on the list, trailing Slim by US$12.5 billion. The Microsoft co-founder added US$7 billion to his net worth as Microsoft shares rose 2.9 per cent.

Microsoft stock accounts for less than 20 per cent of the billionaire's fortune.

Warren Buffett, 82, lost his title as the world's third-richest man to Ortega on August 6. The Berkshire Hathaway chairman gained US$5.1 billion during the year.

The billionaire spent much of the year pressing for higher taxes on the wealthy.